NO. 3 CAMBRIAN TRILOBITES 1 73 



Order OPISTHOPARIA Beecher 



Genus AGRAULOS Corda 



AGRAULOS STATOR, new species 



Plate 36, fig. 6 



Dorsal shield elongate, suboval in outline, moderately convex, and 

 with a narrow, strongly defined, axial lobe. Cephalon transversely 

 semicircular, marginal rim narrow, genal angles rounded. The 

 facial sutures cut the rounded genal angle and extend inward with 

 a sigmoid curve to the base of the small eye lobes; in front of the 

 eye lobes they curve outward a very little and then inward so as to 

 cut the anterior rim of the cephalon on a line with the base of the 

 eyes. Glabella truncato-conical, a little more than one-half the 

 length of the cephalon, and marked by three pairs of shallow furrows 

 separated by a narrow, faint median ridge; occipital furrow and 

 ring narrow and clearly defined; fixed cheeks broad and merging 

 anteriorly into the broad and long, moderately convex and rounded 

 frontal limb; posteriorly the fixed cheeks merge into their postero- 

 lateral limbs, which extend outward from the base of the palpebral 

 lobe to the genal angles ; a rather strong furrow outlines a narrow 

 posterior border which merges into the outer rim of the cephalon at 

 the genal angles ; palpebral lobes small, situated nearly opposite the 

 anterior end of the glabella and with a narrow palpebral ridge 

 extending inward across the broad free cheek to the strong dorsal 

 furrow about the glabella ; free cheeks of medium size and separated 

 from the fixed cheeks only by a small, short eye. 



Thorax with 22 nearly transverse segments ; axial lobe narrower 

 than the pleural lobes, and with a well-defined node near the dorsal 

 furrow on each side; pleural lobes with a strong, narrow furrow 

 extending from near the dorsal furrow along the central part of the 

 segment nearly to its rounded end ; the anterior half of each segment 

 has a smooth faceted surface which greatly facilitated the rolling 

 up of the animal. 



Pygidium small and marked only by one or two rings on the large 

 axial lobe. Surface apparently minutely punctate. 



Dimensions. — The relative size of the various parts of the dorsal 

 shield is shown by the figures. The largest specimen has a length of 

 13 mm. for the cranidium and a total length of 38 mm. 



Observations. — Comparing this species with the genotype, A gr au- 

 las ceticephalus Barrande, we find that it is similar in general form 

 and in having a nearly smooth glabella, a large number of thoracic 

 segments, and very small pygidium. 



